It is important to differentiate between Coeliac Disease (mediated by IgA and IgG antibodies) and wheat allergy that is mediated by IgE antibodies. For further information on Wheat Allergy see the ALLSA Patient Information Sheet on "Wheat Allergy".
How common is Coeliac Disease?
Coeliac Disease is more prevalent than previously believed and is frequently under-diagnosed, particularly in adults who may present with subtle symptoms. In some countries the incidence is as high as 1 in 200 (Sweden) or 1 in 10,000 (Denmark). The incidence in South Africa has not been ascertained, although it is most probably under-diagnosed.
Coeliac Disease is one of the commonest life-long disorders in Western countries. The prevalence of this condition is increased in a number of conditions, such as insulin-dependent diabetes mellitus, Down's syndrome, selective IgA deficiency and certain auto-immune disorders (e.g. thyroid disease, Addison's disease, rheumatoid arthritis, Sjogren's disease).
What are the symptoms of Coeliac Disease?
The condition usually manifests in the first few years of life following the introduction of cereals into the diet. However, due to a greater understanding of the disease process and the more widespread use of the blood tests, increasing numbers of cases are being detected first in adulthood.
Typical cases of CD present at the age of 6-24 months with symptoms of intestinal malabsorption, impaired growth, abnormal stools, abdominal distension, muscle wasting, hypotonia, poor appetite or unhappy behaviour. In adults, the symptoms of CD may be highly varied and range from severe weight loss and diarrhoea with bulky offensive stools, to subtle complaints of cramps, abdominal bloating, flatulence and even constipation. These individuals are often mistakenly diagnosed as having an irritable bowel syndrome. Recurrent oral aphthous ulcers are common and should arouse suspicion of the condition.
Dermatitis herpetiformis is a variant of Coeliac Disease in which clusters of itchy blisters occur, usually over the buttocks, knees and elbows.
On the other hand, gluten allergy (which is IgE-meditated can manifest later in life with a wide range of presentations. Atypical manifestations include intestinal complaints such as recurrent abdominal pain or extraintestinal manifestations such as short stature, persistent iron-deficiency anaemia, folate deficiency anaemia or a calcium metabolism disturbance.
How is Coeliac Disease diagnosed?
There are a range of blood tests that have been introduced internationally over the past few years that can be used to support the diagnosis of CD.
These tests offer simple and fast tools to investigate patients with suspected CD. They are particularly recommended for selected screening of risk groups, such as relatives of CD patients, undiscovered CD patients, and patients who are affected by a related disease such as malabsorption or diabetes mellitus. These tests, and in particular the AGA assays, are also very useful in monitoring the compliance to a gluten-free diet, as any increase in the levels of the antibodies indicates exposure to gliadin in the diet.
These assays are available at a number of private pathology laboratories throughout South Africa.
The widespread use of these tests has shown not only that CD is relatively common in Western countries but that it is characterised by a higher degree of clinical variability than previously thought. However, none of these assays have shown 100% accuracy in diagnosing the condition.
The small intestinal mucosal biopsy therefore remains the cornerstone for diagnosis and any provisional diagnosis of Coeliac Disease must be confirmed by this biopsy. The procedure is safe and usually performed at the time of gastrointestinal endoscopy. However, the sampling variations sometimes require several biopsies.
Treatment of Coeliac Disease
The first line of treatment is the complete removal of gluten from the diet. This usually entails life-long avoidance of all cereals containing gluten, including wheat, oats, rye and barley. Individuals on any avoidance diet are at risk of developing deficiencies of micro-nutrients (e.g. thiamine, riboflavin, niacin, iron, selenium, chromium, magnesium, folacin, phosphorus and molybdenum). It is therefore essential that patients with gluten allergy be managed in collaboration with a dietitian. Information on gluten-free diets is becoming increasingly available worldwide. Gluten free products are also becoming more abundant and more easily available.
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